JP2005088426A - Injection molding machine capable of adding additive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection molding machine which is capable of improving injection molding efficiency by adding a fluid additive to a raw material resin and continuously supplying the mixture to a plasticization device and controlling a foam molding process by adjusting a pressure to be applied to the raw material resin without the necessity of a pressurizing device. <P>SOLUTION: This injection molding machine comprises at least a multi-stage hopper 103 with the interior divided into not less than two stages; a plasticization cylinder 105 communicating with a bottom stage 152 of the multi-stage hopper 103; and a screw 1 rotatably arranged inside the plasticization cylinder 105. In addition, an additive injection hole is formed in the screw 1 and thus the fluid additive can be injected into the plasticization cylinder 105. Further, the fluid additive injected into the plasticization cylinder 105 flows into the multi-stage hopper 103 to be added to the raw material resin, and the spent fluid additive is recovered through an additive recovery circuit 180 while being subjected to a pressure adjustment. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an injection molding machine capable of adding an additive to a raw material resin. More specifically, a fluid additive is added to a raw material resin in a plasticizing cylinder and a hopper that temporarily stores the raw material resin. In addition, raw material resin with fluid additive added can be continuously supplied to the plasticizing cylinder, and additives that can be recovered while adjusting the pressure inside the plasticizing cylinder are added. It relates to a possible injection molding machine.

  In the injection molding to obtain a resin molded product, there are various purposes for coloring the raw material resin, for lowering the glass transition temperature of the difficult-to-melt raw material resin to facilitate melting of the raw material resin, or for foaming purposes. Additives are added. As a method of adding a fluid additive such as gas or liquid (hereinafter referred to as fluid additive) to the raw material resin, (1) a fluid is applied to a screw disposed in a plasticizing cylinder (heating cylinder). A structure for injecting and adding an additive injection path and injection hole, (2) a structure for injecting and adding a fluid additive injection nozzle in a plasticizing cylinder, and (3) an unmelted raw material A configuration in which a resin and an additive are put into a pressure resistant container and left under a pressurized condition for a certain period of time to allow the additive to permeate and diffuse into the raw material resin is employed.

  For example, the fluid additive injection hole is formed and added to the screw of (1), for example, the fluid additive is introduced from a gas introduction hole formed at one end of the screw, and the screw is passed through the stirring unit. A configuration (see Patent Document 1) of adding to the raw material resin in the plasticizing cylinder from a gas supply hole that opens in the wall surface is proposed, and an inert gas is not added to the gas conduction hole formed inside the screw. Introduced and discharged to a position where the raw material resin is almost dissolved, and then removed moisture and decomposition gas generated in the heating cylinder by flowing in the heating cylinder in the opposite direction to the flow of the raw resin (Patent Document) 2) has also been proposed.

  However, in the configuration described in Patent Document 2, the raw material resin may enter the gas discharge hole in the heating cylinder to cause clogging. In order to prevent this, a large amount of high-pressure gas is flowed in advance before the injection molding operation to blow away the residue in the gas discharge holes, and after the injection molding operation is finished, the raw material resin remains even after the supply of the raw material resin is stopped. It is necessary to perform gas blow so that it does not solidify. In addition, although there is no such description in patent document 1, it is thought that the same operation is required.

  As a configuration that does not require the operation, there has been proposed a configuration in which a route for an additive (colorant) is formed at the center of the screw and a check valve is disposed at the tip of the screw (see Patent Document 3). According to this configuration, the check valve can prevent the additive from flowing into the screw, but it is necessary to dispose the check valve at the tip of the screw, which complicates the screw structure and lengthens the plasticizing cylinder. It is thought that it is necessary to lengthen the length, and the injection apparatus becomes larger.

  (2) As a configuration for injecting and adding a fluid additive injection nozzle in a plasticizing cylinder, for example, a multi-stage type in which a plurality of stages including a feed portion, a compression portion, and a metering portion are formed. The flow control part with high flow resistance of the molten resin is formed between the feed part of the front end side stage and the metering part of the rear end side stage, and a gas supply path is provided near the feed part of the front end stage. From here, a configuration in which a gaseous additive is injected has been proposed (see Patent Document 4). According to such a configuration, since the starvation state of the molten resin is generated by the flow control unit of the screw in the vicinity of the gas supply path, the required amount of gaseous additive is added to the molten resin with reproducibility. Can do. However, the multi-stage type screw in which the flow control unit is formed has a complicated screw structure, and the screw length is long and the injection molding machine becomes large.

  Generally, in the configuration in which the injection nozzle is formed in the plasticizing cylinder, it is necessary to reduce the pressure of the raw material resin in order to prevent the injection nozzle from being crushed by the pressure of the raw material resin. For this reason, a left-handed screw element is formed on the upstream side of the injection nozzle, or the valley diameter of the screw is rapidly reduced. However, this requires a longer screw length, which increases the size of the plasticizing cylinder. Also, in the configuration where the injection nozzle protrudes into the plasticizing cylinder, it is necessary to form notches in the screw flight in order to prevent breakage, and the plasticizing cylinder and screw have a special structure, depending on the case It is also necessary to change the base length of the molding machine. Furthermore, when a notch is formed in the screw, a back flow of the raw material resin occurs, the residence time of the raw material resin in the plasticizing cylinder becomes long, and there is a possibility that thermal decomposition of the raw material resin is promoted. On the other hand, if the injection nozzle is retracted from the inner wall surface of the plasticizing cylinder, the raw material resin may stay in the depression and promote the generation of resin burns.

  In the method (3) in which the raw material resin and additive in an unmelted state are put into a pressure vessel and the additive is permeated and diffused into the raw material resin, the additive is generally added using a separate container. Therefore, the supply of the raw material resin to the injection molding machine must be a batch system. In the batch method, each installed container is impregnated with gas, so it takes time for material change, mold change, and the like, which causes a significant decrease in the productivity of the resin molded product. In addition, in the production plan, the batch method requires a lot of management, and there is a problem of processing the remaining material.

  On the other hand, if it is a continuous type, only the necessary amount of raw material resin pellets can be used, which is advantageous in terms of the above points. For this reason, for example, a plurality of chambers are arranged in series, the upper chamber is supplied with the raw material resin from the hopper, and the raw material resin is gas-impregnated, and the lower chamber is the raw material that is gas-impregnated in the upper chamber There has been proposed a configuration in which gas is impregnated in the upper chamber while the raw material resin is supplied from the lower chamber to the plasticizing cylinder (see Patent Document 5). According to this configuration, during the injection molding operation, a predetermined amount or more of the raw material resin is stored in a saturated state in which gas impregnation is performed, and the raw material resin can be continuously supplied to the plasticizing cylinder.

  By the way, the solubility of the gas in the resin at a constant temperature is proportional to the pressure (Henry's law), but it is known that the solubility decreases as the temperature rises. For this reason, the resin temperature rises inside the plasticizing cylinder. Then, the solubility of the gas in the resin decreases, and the gas is easily degassed and easily discharged to the feed portion. In order to prevent this and ensure the solubility of the gas in the molten resin, a structure in which the gas is pressure-impregnated into the resin in the cylinder is required. However, Patent Document 5 does not disclose a configuration for controlling the amount of gas impregnation with respect to molten resin, semi-molten resin, or unmelted resin pellets in the plasticizing cylinder, particularly in the compression portion.

  For example, in foam molding performed by impregnating a raw material resin with a gaseous additive or the like, the surface additives and the surface properties and structure of the final resin molded product are developed by removing the gaseous additive that is no longer needed during injection molding. . The removal of the unnecessary part of the fluid additive is generally performed by, for example, depressurizing the molten resin in a shaping apparatus such as the inside of a mold.

  As a configuration for reducing the pressure of the molten resin, for example, a pressure reducing mechanism is formed in the flow path of the molten resin such as a gear pump or a nozzle arranged at the tip of the injection unit to grow the foam nuclei, and then the bubbles are grown. A configuration for reducing the pressure to atmospheric pressure has been proposed (see Patent Documents 6 and 7). In addition, the counter pressure method in which pressure is applied to the inside of the mold is used to control foaming until the molten resin injected into the mold reaches the end of the mold. In order to control, a configuration has been proposed in which supercritical carbon dioxide is injected into the mold in advance at a pressure that can suppress foaming of the resin, and then molten resin to which supercritical carbon dioxide is added is injected. (See Patent Documents 8 and 9).

  According to these configurations, the fluid additive added to the molten resin is depressurized from the molten resin while adjusting the pressure in the mechanism or mold attached to the tip of the plasticizing cylinder, and the resin molded product Although the surface properties and internal structure are controlled, this pressure adjustment is performed separately in the plasticizing cylinder and in the shaping device such as a die and a mold. When injecting into a mold in a non-foamed state, a device for applying pressure (applying counter pressure) to the mold is required to reduce the pressure difference between the pressure in the plasticizing cylinder and the mold. Further, even when injecting into a mold in a foamed state, a device for pressurizing the inside of the mold is required to control the foamed state. As described above, the foam molding has a problem that a pressurizing device is required and the facility becomes large.

  As an injection molding machine that does not require such a pressurizing device, for example, a device in which a supercritical carbon dioxide supply unit and a decompression unit are provided in an injection molding machine and both are separated by a gate valve is used. An injection molding machine has been proposed in which carbon dioxide is gently removed by a decompression device to prevent foaming (see Patent Document 10). However, a gate valve that divides the injection molding machine into two sections is arranged, or the screw is reversed. The configuration is complicated, such as forming a flight in the screw direction.

Japanese Patent Laid-Open No. 10-278081 JP 2001-341152 A JP 2003-48239 A JP 2002-326259 A JP 2000-127194 A US Pat. No. 6,284,810 U.S. Pat. No. 3,796,796 Japanese Patent Laid-Open No. 11-245254 JP 2001-341152 A JP 2000-187192 A

  The problem to be solved by the present invention is that a fluid additive is added to a raw material resin with a simple structure and can be continuously supplied to a plasticizer to improve the efficiency of injection molding and to perform incidental operations such as production control. Providing an injection molding machine that can be reduced, or complicating the structure of the plasticizing cylinder, or without requiring a fluid pressure injection device for the shaping device, the partial pressure of the additive in the raw resin Is to provide an injection molding machine capable of controlling the injection state of the additive.

  In order to solve such a problem, the invention described in claim 1 forms a long hole in the axial direction of the screw for injection molding disposed in the plasticizing cylinder for plasticizing the raw material resin, An additive supply pipe for supplying a fluid additive to be added to the raw material resin is loosely inserted into the long hole so that viscous molten resin does not enter between the inner wall surface and the outer surface of the long hole of the screw. Although it is possible, the gist is that an additive injection hole in which a porous member capable of passing the fluid additive is inserted is formed.

  Further, in the invention according to claim 2, in the vicinity of the tip in the direction in which the molten resin of the plasticizing cylinder for plasticizing the molten resin is injected, there is a viscous space between the inner wall surface of the plasticizing cylinder and the outside. Although the intrusion of the molten resin is impossible, the gist is that an additive discharge hole into which a porous member capable of passing the fluid additive is inserted is formed.

  Here, as described in claim 3, the porous member is preferably made of a porous metal or a porous ceramic.

  In the invention according to claim 4, a plurality of airtight containers capable of temporarily storing the raw material resin are arranged in series through the raw material resin route and the fluid additive route added to the raw material resin, Among the plurality of sealed containers, the sealed container disposed at the lowermost part communicates with a plasticizing cylinder that plasticizes the raw material resin, and the plasticizing cylinder is added with a fluid additive added to the raw material resin. The injection molding screw in which the agent injection hole is formed is disposed, and the fluid additive injected into the plasticizing cylinder from the additive injection hole of the injection molding screw is transferred from the lowermost airtight container to the fluid. The gist of the present invention is that the fluid additive is sequentially injected into the upper closed container through the path of the liquid additive, and the fluid additive can be added to the raw material resin in the plasticizing cylinder and in each closed container.

  According to the first aspect of the present invention, since the fluid additive is injected into the plasticizing cylinder from the additive injection hole formed in the screw, it is not necessary to complicate the configuration of the plasticizing cylinder. Moreover, the screw has a very simple structure only by having a configuration in which a porous member is inserted into an additive injection hole which is an opening. For this reason, it becomes possible to simplify the structure of an injection molding machine. Further, unlike the configuration in which the nozzle is provided on the screw, there is no restriction on the position where the additive injection hole is formed, so that it can be formed at an optimal position according to the type of additive or resin. In addition, since the porous member prevents the molten resin from entering the additive supply path, it is easy to handle and has good maintainability.

  According to the second aspect of the present invention, not only the unnecessary portion of the additive can be recovered, but also the unnecessary portion of the additive can be removed by reducing the pressure near the tip of the plasticizing cylinder. By adjusting the partial pressure of the molten resin additive from the tip of the plasticizing cylinder to the nozzle, it becomes easy to control the injection state of the additive. For example, in foam molding in which a fluid additive is added under pressure and then reduced in pressure to foam, the foam pressure can be easily controlled without applying counter pressure by gradually reducing the pressure applied to the molten resin. It becomes. For this reason, equipment for applying counter pressure is not required, and the injection molding equipment can be reduced in size and simplified.

  Here, as described in claim 3, if the porous member is attached to the additive injection hole or additive recovery hole, the structure becomes simple, the processing of the screw and the plasticizing cylinder is easy, and the equipment Cost reduction can be achieved. Moreover, it is excellent in the tolerance with respect to the pressure and temperature of raw material resin, and an appropriate through-hole is easy to be obtained.

  According to the fourth aspect of the present invention, the raw material resin is sequentially transferred through the multistage hopper into which the additive has been injected, and is supplied into the plasticizing cylinder while adding the additive. Resin can be continuously fed into the plasticizing cylinder. For this reason, the production efficiency in the injection molding process can be improved. In addition, since all the paths of the raw material resin including the plasticizing cylinder are in a state where the additive is injected, the saturated state of the additive can be maintained.

  Below, the injection molding machine which can add the additive which concerns on this invention is demonstrated in detail with reference to drawings. FIG. 1 is a view showing a structure of a screw applied to an injection molding machine according to the present embodiment, (a) is a view showing an external structure, and (b) is a cross-sectional view showing an internal structure. .

  As shown in FIG. 1A, the screw 1 includes a feed portion 17 having a small valley diameter, a metering portion 7 having a large valley diameter, and a taper between the feed portion 17 and the metering portion 7. A compression portion 15 having a variable diameter is provided, and screw flights 5 are formed on the outer peripheral surfaces of the portions 7, 15, and 17 over the respective portions.

  As shown in FIG. 1 (b), an additive injection path 3 is formed inside the screw 1. This additive injection path 3 is a long hole-shaped path formed substantially coaxially in the axial direction of the screw 1 and is one end (the right end in the figure. Hereinafter, the “rear end” for convenience). The side where the metering portion 7 is formed (the left end in the figure, hereinafter referred to as “tip” for convenience) is a non-through long hole that is closed. An additive injection hole 9 that communicates the inner wall surface of the additive injection path 3 and the outer peripheral surface of the screw 1 is formed, and an injection hole member 11 is inserted into the additive injection hole 9.

  The injection hole member 11 is made of a porous member that cannot allow a viscous molten resin to enter, but allows a fluid such as a gas or a liquid having a low viscosity to pass therethrough. The diameters of through-holes such as through holes and continuous bubbles required to ensure this function vary depending on the type of fluid additive and molten resin used, particularly the viscosity, and are therefore selected as necessary. . For example, in the case of a viscous resin such as PBT (polybutylene terephthalate) resin, the pore diameter may be 50 μm or less. As the material of the porous member, porous metals such as porous metals and porous aluminum, porous ceramics such as zeolite, and the like can be applied. More specifically, “Metapol-METAPOR (trade name)” (Pontc) Ltd., “Hyporus (trade name)” (manufactured by Kobe Steel, Ltd.), and the like can be applied.

  The position and number of the additive injection holes 9 are determined in consideration of the diffusibility of the fluid additive into the raw material resin. For example, when the diffusibility is low, it is formed in the compression portion 15 or the kneading element, or near the feed portion 17 as shown in FIG. On the other hand, when the diffusibility is high, as shown in FIG. 2B, it is desirable to form the metering portion 7 or the screw tip. Further, these additive injection holes 9 are formed on the surface of the valley of the screw as shown in FIG. 2, and are formed in the screw flight 5 if there is no problem in the strength of the screw flight 5 to form an injection hole member (porous). The material member) may be inserted.

  An additive supply pipe 21 is loosely inserted into the additive supply path 3 of the screw 1. The additive supply pipe 21 is a tubular member, and a fluid additive can be supplied to the additive supply path 3 of the screw 1 through the additive supply pipe 21.

  According to such a screw, since the fluid additive can be injected and added from the screw, it is not necessary to complicate the structure of the plasticizing cylinder such as disposing a fluid additive injection nozzle in the plasticizing cylinder. Further, since only a porous member is inserted into the injection hole 9 in the screw 1, there is no need to make the screw structure complicated. For example, the screw becomes large as a check valve is provided. There is nothing.

  FIG. 3 is a cross-sectional view schematically showing the structure of an injection unit to which the screw is suitably applied, ancillary equipment, and the flow of a fluid additive. The arrow a in the figure indicates the flow of the fluid additive, and the arrow b indicates the flow of the raw resin.

  The outline of the configuration of the injection unit 100 and the flow of the fluid additive will be described. The injection molding unit 100 temporarily stores the raw resin and adds the fluid additive, and is supplied from the multi-stage hopper 103. And a plasticizing cylinder 105 for plasticizing the received raw material resin. The screw 1 is disposed inside the plasticizing cylinder 105, and the screw rotates to plasticize the raw material resin. The plasticized molten resin is supplied from a nozzle 201 disposed at the tip of the plasticizing cylinder 105. Configured to be injected.

  Further, the fluid additive stored in the fluid tank 109 or the like is sent out after its temperature and pressure are adjusted by the temperature control and pressure circulation device 107, and from the additive injection hole 9 through the additive supply path 3 of the screw 1. It is injected into the plasticizing cylinder 105. The fluid additive injected into the plasticizing cylinder 105 flows into the multi-stage hopper 103 and is added to the raw resin, and the unnecessary part is recovered and the temperature and pressure are adjusted again by the temperature control and pressure circulation device 107. Configured to be sent out.

  Note that the temperature of the fluid tank 109 storing the fluid additive, the fluid additive stored in the fluid tank 109, and the temperature and pressure of the fluid additive recovered through the additive recovery circuit are adjusted and sent out. The heating circulation device 107 is configured by any known temperature adjusting means, pressure adjusting means, or a combination thereof.

  Next, each component will be described. The multi-stage hopper 103 is configured by combining a plurality of pressure-resistant airtight containers whose interior is divided into at least two stages or a single pressure-resistant airtight container. Here, an example in which the inside is divided into three stages of an upper stage 150, a middle stage 151, and a lower stage 152 is shown. The stages 150, 151, 152 of the multi-stage hopper 103 are arranged in series in the vertical direction via the partition walls 153, 154. These partition walls 153 and 154 can be slidably opened and closed in the direction of arrow c. When opened, each stage communicates so that the raw material resin can move, and when closed, each stage 150, 151, 152 is airtight. Can be maintained.

  In addition, the upper stage 150 communicates with the raw material supply path 161 and the exhaust path 162 via partition walls 159 and 160 that can be opened and closed in a sliding manner in the direction of arrow c. The raw material supply path 161 is a path for supplying the raw material resin from the outside to the upper stage 150 of the multistage hopper 103, and the raw material resin is supplied into the upper stage 150 by opening the partition wall 159 by a blower type or a vacuum suction type. The exhaust path 162 is a path communicating with outside air, and when the partition wall 160 is opened, the gas inside the upper stage 150 can be discharged to the outside. It is desirable that gas exhausting means such as a filter 163 capable of removing dust or harmful gas is disposed in the exhaust path 162. Moreover, when these partition walls 159 and 160 are closed, the inside of the upper stage 150 can be maintained in an airtight state.

  The middle stage 151 is a space (container) formed between the partition wall 153 disposed between the upper stage 150 and the partition wall 154 disposed between the lower stage 152, and the raw resin is disposed inside the upper stage 150. When the partition wall 153 is opened in a state in which the raw material is stored, the raw resin drops by gravity and can be stored inside the middle stage 151. When the partition wall 154 is opened while the raw material resin is stored in the middle stage 151, the inside of the middle stage 151 The raw material resin is configured to fall into the lower stage 152.

  The lower stage 152 communicates with the middle stage 151 via the partition wall 154 on the upper side and communicates with the internal space of the plasticizing cylinder 105 on the lower side. The raw material resin dropped and stored from the middle stage 151 is configured to be supplied into the plasticizing cylinder 105 from below.

  In addition, as the slidable openable and closable partitions disposed between the respective stages 150 to 152 of the multi-stage hopper 103 and the upper stage 150 and the raw material supply path 161 and the exhaust path 162, various well-known various types that are operated by an air cylinder or the like. A path opening / closing means can be applied. These partition walls are not limited to the slide type as long as they can pass the raw resin and fluid when opened, and can maintain an airtight state when closed, such as an airtight butterfly valve. May be.

  Further, the upper stage 150 and the middle stage 151 and the middle stage 151 and the lower stage 152 communicate with each other through pressure adjustment paths 155 and 156 through which fluid can pass. These pressure regulation paths 155 and 156 are provided with a pressure regulation valve 170, and this pressure regulation valve allows the fluid to pass therethrough (that is, to flow in) when the pressure of the fluid flowing in becomes higher than a predetermined pressure. Side fluid pressure is maintained at a predetermined pressure). Note that the pressure adjustment path 155 that connects the upper stage 150 and the middle stage 151 branches in the middle, and the branched side communicates with the temperature control heating circulation device 107 as an additive recovery circuit 180a (not shown).

  In the plasticizing cylinder 105, the screw 1 is disposed. The fluid additive delivered from the temperature control and pressure circulation device 107 is supplied to the additive supply path 3 of the screw 1, and the amount not injected into the plasticizing cylinder 105 from the additive injection hole 9 is the additive. It is configured to be recovered from the recovery circuit 180c to the temperature control and pressurization circulation device 107. That is, the additive supply pipe 21 loosely inserted in the additive supply path 3 is fixed so as not to rotate even when the screw 1 rotates, and communicates with the temperature control and pressure circulation device 107. Further, the additive supply path 3 communicates with the temperature control and pressurization circulation device 107 via the seal valve 185 and the additive recovery circuit 180c. The seal valve 185 has a configuration capable of communicating with the additive recovery circuit 180c while maintaining the airtightness of the rotating portion even when the screw 1 rotates, and various known seal valves can be applied. .

  In the vicinity of the nozzle 201 of the plasticizing cylinder 105 and in the nozzle 201, a plurality of additive discharge holes 202a to 202c, which are through holes communicating with the outside, are formed side by side in the axial direction of the screw 1 (in FIG. 3, 202a, 202b, 202c is shown), the discharge hole member 205 is inserted into these additive discharge holes 202a to 202c. The discharge hole member 205 is formed of the same porous material as that inserted into the additive injection hole 9 of the screw 1.

  These additive discharge holes 202a to 202c communicate with the temperature control and pressure circulation device 107 by the additive recovery circuit 180d through the pressure regulating valves 171a to 171c, respectively. These pressure regulating valves 171a to 171c have the same function as the pressure regulating valve 170 disposed in the pressure regulating paths 155 and 156, and respectively control the pressure inside the nozzle 201 or inside the vicinity of the tip of the plasticizing cylinder 105. Maintain a predetermined pressure.

  The nozzle 201 disposed in the plasticizing cylinder 105 is desirably a shut-off nozzle because it is necessary to adjust the internal pressure of the plasticizing cylinder 105. In the drawing, a shut-off nozzle having a rotor 210 is shown, but the configuration is not limited to this as long as it is a shut-off nozzle.

  The flow of the fluid additive in such a configuration is as follows. The fluid additive is sent out from the temperature control heating circulation device 107 with the temperature and pressure adjusted, and is supplied to the additive injection path 3 of the screw 1 through the additive supply pipe 21. The fluid additive supplied to the additive supply path 3 is injected from the additive injection hole 9 into the plasticizing cylinder 105 and flows into the lower stage 152 of the multistage hopper 103 while filling the plasticizing cylinder 105. To do.

  Here, the temperature of the fluid additive sent out from the temperature control heating circulation device 107 is at least the raw material resin (melted) inside the plasticizing cylinder 105 when injected into the plasticizing cylinder 105 from the additive injection hole 9. It is desirable that the temperature be higher than the temperature that does not significantly impair the fluidity of the resin), and the temperature is adjusted by the temperature-regulating heating circulation device 107 so as to reach such a temperature.

  Of the fluid additive supplied to the additive injection path 3, the amount of the fluid additive that has not flowed into the plasticizing cylinder 105 from the additive injection hole 9 passes through the additive recovery circuit 180 c to the temperature control heating circulation device 107. It is recovered and sent out again after adjusting the temperature and pressure.

  In addition, since the fluid additive adjusted to a predetermined temperature circulates inside the screw 1, the effect of temperature adjustment that maintains the inside of the screw 1 and the plasticizing cylinder 105 at a predetermined temperature is also obtained.

  When a screw having an injection hole in the compression unit 15 or the feed unit 17 is used, the fluid additive is warmed on the inner wall surface of the additive supply path 3 of the screw 1 and then injected into the plasticizing cylinder 105. Therefore, the fluidity of the resin is not hindered. For this reason, in the temperature control heating circulation device 107, a temperature controller for adjusting the temperature of the additive becomes unnecessary, or a problem does not occur even if the temperature controller has a low capacity. Or delicate temperature control becomes unnecessary. In addition, since the fluid additive is injected from the inside of the screw, if it is injected from the vicinity of the feed portion near the multi-stage hopper 103, the temperature of the additive and the temperature of the molten resin are easily brought close to each other.

  When the fluid additive flows into the lower stage 152 of the multi-stage hopper 103 and the internal pressure of the lower stage 152 reaches a predetermined pressure, the fluid additive is a pressure regulating valve of the pressure regulating path 156 that connects the lower stage 152 and the middle stage 151. It passes through 170 and flows into the middle stage 151. For this reason, the predetermined internal pressure of the lower stage 152 is maintained. When the middle stage 151 reaches a predetermined internal pressure due to the fluid additive that has flowed in, the fluid additive passes through the pressure regulation valve 170 of the pressure regulation path 155 that communicates the middle stage 151 and the upper stage 150 and flows into the upper stage 150. . Thereby, the middle stage 151 is maintained at a predetermined internal pressure. Further, when the upper stage 150 reaches a predetermined internal pressure due to the fluid additive that has flowed in, it passes through the pressure regulating valve 170 of the additive recovery circuit 180 a and is recovered by the temperature control heating circulation device 107. For this reason, the inside of the upper stage 150 is maintained at a predetermined pressure, and the recovered fluid additive is sent out again after adjusting the temperature and pressure.

  In this way, the fluid additive supplied from the fluid tank 109 is filled in each stage of the plasticizing cylinder 105 and the multistage hopper 103, and each stage of the plasticizing cylinder 105 and the multistage hopper 103 is maintained at a predetermined internal pressure. Is done. Here, the fluid additive flows through the plasticizing cylinder 105 in the order of the lower stage 152, the middle stage 151, and the upper stage 150 of the multistage hopper, and the internal pressure of each stage is highest in the lower stage 152, and then the middle stage 151, the upper stage. The internal pressure of the upper stage 150 is maintained at a pressure closest to the atmospheric pressure.

  The flow of the raw resin and the operation of adding the fluid additive are as follows.

  The partition walls 159 and 160 between the upper stage 150 and the raw material supply path 161 and the exhaust path 162 are opened, and the raw material resin is supplied from the outside to the upper stage 150 through the raw material supply path 161, and the inflowing gas is exhausted. 162 is released into the atmosphere. When the partition wall 159 between the raw material resin and the raw material supply path 161 is closed, the gas (mainly atmospheric components) in the upper stage 150 is pushed out by the fluid additive flowing in through the pressure adjustment path 155 and exhausted. The gas is discharged from the path 162 to the atmosphere, and the upper stage 150 is filled with a fluid additive. After that, when the partition wall 160 between the exhaust passage 162 is closed, the inside of the upper stage 150 is maintained at a predetermined pressure by the flowing fluid additive.

  Then, the partition wall 153 between the upper stage 150 and the middle stage 151 is temporarily opened, and the raw material resin stored in the upper stage 150 is dropped into the middle stage 151. When the partition wall 153 is temporarily opened, the internal pressures of the upper stage 150 and the middle stage 151 are temporarily the same, but when the partition wall 153 is closed, the predetermined pressure is again maintained. If the raw resin is dropped on the middle stage 151 and left for a predetermined time, the fluid additive penetrates and diffuses into the raw resin, and the addition process proceeds. Thereafter, the partition wall 154 between the middle stage 151 and the lower stage 152 is temporarily opened to drop the raw material resin added with the fluid additive into the lower stage 152, and is supplied from the lower stage 152 into the plasticizing cylinder 105. To be plasticized. Since the inside of the lower stage 152 is also filled with the fluid additive, the raw material resin is maintained in a state where the fluid additive is added.

  While the fluid additive diffusion process is proceeding in the middle stage 151, the raw material resin is supplied into the upper stage 150 by the above operation. If the partition wall 153 between the upper stage 150 and the middle stage 151 is closed, even if the partition walls 159 and 160 between the upper stage 150 and the raw material supply path 161 and the exhaust path 162 are opened, atmospheric components are contained in the middle stage 151. Even if there is a gap in the partition wall 153, the inside of the middle stage 151 is maintained at a pressure higher than the atmospheric pressure, so that atmospheric components do not flow into the middle stage 151. Thus, the operation of supplying the raw material resin to the upper stage 150 does not affect the progress of the fluid additive addition process in the middle stage 151.

  When the screw 1 rotates in the plasticizing cylinder 105, the raw material resin is plasticized and injected from the nozzle 201 into a mold (not shown). The fluid additive which is no longer needed at this time is discharged from the additive discharge hole 202 formed in the vicinity of the nozzle 201 and the nozzle of the plasticizing cylinder 105, and is recovered by the temperature control heating circulation device 107 through the additive recovery path 180d. Is done. Then, the temperature and pressure are adjusted by the temperature control heating circulation device 107 and sent out again.

  When the injection molding operation proceeds and the raw material resin supplied to the lower stage 152 decreases to a certain amount or less, the raw material level sensor 207 disposed in the lower stage 152 detects this, and between the middle stage 151 and the lower stage 152. The partition wall 154 is opened again to supply the raw material resin into the lower stage 152. When the amount of raw resin stored in the middle stage 151 is small or empty, the partition wall 153 between the upper stage 150 and the lower stage 152 is temporarily opened to supply the raw resin to the middle stage 151. When the amount of raw material resin stored in the upper stage 150 becomes small or empty, the raw material resin is supplied to the upper stage 150.

  In this way, the supply of the raw material resin to the upper stage 150 and the process of adding the fluid additive in the middle stage 151 can be performed independently and in parallel without being affected by each other. The raw material resin thus obtained can be continuously supplied to the lower stage 152, and a state where a predetermined amount or more of the raw material resin is always stored in the lower stage 152 can be maintained. Therefore, the raw material resin can be continuously supplied to the plasticizing cylinder 105, and the efficiency of the injection molding process can be improved.

  Since the upper stage 150 is also maintained in a state filled with the fluid additive except during the supply of the raw resin, the additive can be added in the upper stage 150 in parallel. Further, while the raw material resin is being supplied to the upper stage 150, in order to reduce the waste of the fluid additive, the fluid additive is not sent from the pressure adjustment path 155 to the upper stage, and is recovered from the additive recovery circuit 180b. It may be.

  Further, since the inside of each stage of the multistage hopper 103 is maintained at a pressure higher than atmospheric pressure, even if there is a gap in the partition wall, impurities such as atmospheric components and dust do not enter from there. In particular, the uppermost stream of the fluid additive is the plasticizing cylinder 105, and since the internal pressure of the plasticizing cylinder 105 is the highest, the atmosphere in the plasticizing cylinder 105 where it is not desired to touch the molten high-temperature resin. There is almost no component (for example, oxygen), and the quality of the resin molded product can be improved.

  Of the fluid additive added to the raw resin, the unnecessary part is collected as follows. As shown in FIG. 3, a plurality of additive discharge holes 202 are formed in the axial direction of the screw 1 in the vicinity of the nozzle 201 and the nozzle 201 of the plasticizing cylinder 105. The pressure regulating valves 171a to 171c disposed in the additive recovery circuit 180d communicating with the inside of the plasticizing cylinder 105 or the nozzle 201 are arranged in the order of 171a, 171b, and 171c in the order toward the tip of the nozzle 201. The pressure is adjusted to be kept low.

  For this reason, the molten resin sent out by the screw 1 is removed from the additive discharge holes 202a, 202b, 202c so that the pressure of the fluid additive gradually decreases. The same effect as that obtained by controlling to gradually reduce the pressure difference inside the control cylinder and the pressure inside the mold can be obtained. Therefore, the foaming state of the raw material resin can be controlled without providing a separate pressure device in foam molding.

  It should be noted that the predetermined pressure of the pressure regulating valve disposed in each additive recovery circuit may be controlled so as to change during injection of the molten resin. That is, for example, at the start of injection, a predetermined pressure is set high to suppress foaming and inject in an unfoamed state, and the control is performed so that the predetermined pressure is lowered as injection proceeds. It becomes possible to inject the resin into the mold in a foamed state. At the same time, the foaming state in the mold can be controlled.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, in the said embodiment, although the injection unit assembled | attached to an injection molding machine is shown, you may arrange | position to an extrusion molding machine. Moreover, although the multistage hopper shows the structure divided into three stages, it may be two stages or four stages or more, and the number of stages is not limited.

It is the figure which showed the structure of the screw applied to the injection molding machine which concerns on this invention, (a) is the top view which showed the external structure, (b) is sectional drawing which showed the internal structure. It is the figure which showed the position where the additive injection hole of a screw is formed, (a) is the figure which showed the structure formed in a compression part, (b) The structure which formed a metering part and a screw front-end | tip. . It is the figure which showed typically the structure of an injection unit, incidental equipment, and the flow of the fluid additive.

Explanation of symbols

1 screw 103 multi-stage hopper 105 plasticizing cylinder 180 additive recovery circuit

Claims (4)

  Addition of forming a long hole in the axial direction of an injection molding screw disposed in a plasticizing cylinder for plasticizing the raw material resin and supplying a fluid additive to be added to the raw material resin into the long hole A porous member in which a viscous molten resin cannot be infiltrated between the inner wall surface and the outer surface of the long hole of the screw, but through which the fluid additive can pass is inserted. An injection molding machine capable of adding an additive, characterized in that an additive injection hole inserted therein is formed.   In the vicinity of the tip in the direction of injection of the molten resin of the plasticizing cylinder that plasticizes the molten resin, it is impossible to enter the viscous molten resin between the inner wall surface and the outside of the plasticizing cylinder. An injection molding machine to which an additive can be added, wherein an additive discharge hole into which a porous member capable of passing a fluid additive is inserted is formed.   The injection molding machine according to claim 1 or 2, wherein the porous member is made of porous metal or porous ceramics.   A plurality of airtight containers capable of temporarily storing the raw material resin are arranged in series through the path of the raw material resin and the path of the fluid additive added to the raw material resin, and the bottom of the plurality of sealed containers The airtight container disposed in the cylinder communicates with a plasticizing cylinder that plasticizes the raw material resin, and the plasticizing cylinder is formed with an additive injection hole for adding a fluid additive to be added to the raw material resin. A molding screw is disposed, and the fluid additive injected into the plasticizing cylinder from the additive injection hole of the injection molding screw is sequentially passed through the fluid additive route from the lowermost airtight container to the upper side. An injection molding machine capable of adding an additive, wherein the additive is injected into a sealed container and a fluid additive can be added to the raw material resin in the plasticizing cylinder and in each sealed container.

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